I also experienced a very strange behavior. No clue if it is related.
Last week I put 50€ on my newly created account, with which I haven't traded much in the meantime, just 4 transactions in total:
4 sell 0.28050000 78.99503 € 22.15811 € EUR 2013-04-01 15:45:34
3 buy 0.28050000 78.16500 € 21.92528 € EUR 2013-04-01 15:29:13
2 sell 0.30000000 73.29900 € 21.98970 € EUR 2013-03-30 17:06:02
1 buy 0.63459854 78.78997 € 50.00000 € EUR 2013-03-28 10:32:56
Imagine you start from 50€ with which you buy for 50€, and then sell, buy and sell for 22€, you would expect there to be 22€ on the account, right? But my account is still empty! For the last transaction the money never arrived, although the transaction history says I sold for 22.15811€.
It all happened in a period of instability of the exchange, but my conclusion is that selling on bitcoin-24 is not safe and I'm glad that I didn't try it with a bigger amount.
Posted it earlier at:
https://bitcointalk.org/index.php?topic=166914.0